Affine Caesar cipher is a generalization of the Caesar cipher, with the following

form:

C = E([a,b],p) = (ap + b) mod 26

What would be the limitations for the possible values of a and b? Explain why.

Provide your answer as a general statement.

Based on your answer to the first part of this question, how many distinct

affine Caesar cipher exist? Explain your answer.

The following ciphertext has been generated with an affine Caesar cipher.

Break the code. (It is important to show all the cryptanalysis steps you

perform, and not just writing the final answer.)

RUUBE JNRJH RWNBA QJWBH ODIEJ

WRCIJ SPIJS SJWUW JLDJE NV

Hint:

First, indicate the first two most frequent letters in the cipher.